In Tex-Mex cooking, the dried poblano pepper known for its mild, raisiny flavor is an ancho.
Ancho is the name used for a ripe poblano after it has been dried. Fresh poblanos are usually dark green and moderately mild, while mature poblanos can turn reddish before drying. The drying process concentrates their fruitiness and produces the wrinkled, dark reddish-brown chile associated with ancho flavor.
Anchos are commonly ground into chile powders or soaked and blended into sauces, stews, marinades, and enchilada-style preparations. Their flavor is generally sweet, earthy, and lightly smoky rather than aggressively hot.
Ancho is often confused with chipotle, but chipotle is a smoked, dried jalapeño. Guajillo and pasilla are also different dried chiles, each with its own flavor and heat profile. The word ancho therefore identifies both a particular pepper variety and its dried culinary form.